Disentangling Jet Modification in Jet Simulations and in Z+Jet Data

by Quinn Brodsky (Massachusetts Institute of Technology)

Monday 6 Dec 2021, 16:00 → 18:00 Europe/Zurich

Zoom (CERN)

The selection of jets in heavy-ion collisions based on their quenched $p_T$ is known to bias towards jets that lost little energy. We illustrate this explicitly in a simplified Monte Carlo study in which it is possible to identify the same jet before and after quenching. We find that selecting a sample of jets based on their quenched $p_T$ yields a sample of jets whose fractional energy loss is substantially smaller than would have been the case if it were possible to select a sample of jets based upon their $p_T$ before quenching. This has substantial impacts on jet structure and substructure observables, and dramatically reduces the observable consequences of medium response in a sample of jets selected based upon their quenched $p_T$, since the jets that are selected are those that lost little energy and hence created little medium response. We then show that the same qualitative effect can be seen in Z+jet events, and that selecting jets in such events based on either the jet $p_T$ or the boson $p_T$ provides an experimentally-accessible way to quantify the role of selection biases in jet observables. Selecting such jets based on the Z boson $p_T$ removes the bias towards jets that lost little energy, making the observable impact of medium response apparent.

Based on arXiv:2110.13159